1. Field of the Invention
The present invention relates to a method of forming a pellet of condensed gas, such as hydrogen, tritium or deuterium, in situ within the tube or barrel of a pneumatic injector or a so-called pipe gun. One way of fuelling present experimental reactors or plasma devices, so-called "tokamaks" and other similar devices as well as future fusion reactors, is to inject solid pellets of fuel material. According to present theories of the pellet-plasma interactions such pellets should be given velocities up to 10.sup.4 m/sec. in fusion reactors, whereas substantially lower velocities suffice for present experimental devices.
2. Description of the Prior Art
The prior art within this field is disclosed in for example J. Lafferanderie et al., Proc. 14th SOFT 1986, p. 1367, S. K. Combs et al., Rev. Sci. Instr. 57, 1986 p. 2636, V. Andersen et al., Proc. 11th SOFT 1980, S. L. Milora et al., Rev. Sci. Instr. 57, 1986 p. 2356. and O. Lazare, These, Universite de Paris.Sud, Orsay n'd'Ordre 704. Lafferanderie et al. discloses a method of in situ condensation of hydrogen isotopes in the barrel or tube of a pneumatic pellet injector or pipe gun so as to produce a pellet therein ready for firing. The pellet is formed within a freezing cell made from copper and provided with heaters. The freezing cell which is cooled by liquid helium is mounted between stainless steel flanges which are welded to adjacent tube sections. Insulating spaces which may be filled by a thermal insulate, are defined between the freezing cell and the respective flanges. The gas to be condensed is supplied to the freezing cell from both sides.